## Friday, March 23, 2012

### Keynes, Probability and a Schrödinger's Jesus

Another of the blogs we read and don't link to often enough.
From William M. Briggs, Statistician to the Stars!:

Bayes Theorem Proves Jesus Existed And Didn’t Exist
In his shockingly neglected, A Treatise on Probability John Maynard Keynes put his finger on the difficulty people have with probability, particularly Bayes’s Theorem:
No other formula in the alchemy of logic has exerted more astonishing powers. For it has established the existence of God from the premiss of total ignorance; and it has measured with numerical precision the probability the sun will rise to-morrow.
Probability carries with it “a smack of astrology, of alchemy.” Comte, Keynes reminds us, regarded the application of the mathematical calculus of probability as “purement chimérique et, par conséquent, tout à fait vicieuse.”

That last word, dear reader, is vicious; a word which was laughed off in the mad rush towards the utopia of Quantification an era which Comte, incidentally, and despite his intentions, helped usher in. We are, at this moment, mere moments away before a number must by law be attached to every judgment of uncertainty. We are already there in all “scientific” uses of statistics where a thriving Pythagorean cult, complete with arcane initiations and occult formulae, worships the number 1 in 20.

So you won’t be surprised when I tell you there is not one, but two books which argue that a fixed, firm number may be put on the proposition God Exists. The first by Stephen Unwin is called The Probability of God: A Simple Calculation That Proves the Ultimate Truth, in which he uses Bayes’s theorem to demonstrate, with probability one minus epsilon, (the Christian) God exists.

This is countered by Proving History: Bayes’s Theorem and the Quest for the Historical Jesus by the very concerned Richard Carrier (pictured above), whose uses Bayes’s theorem to prove, with probability one minus epsilon, that the Christian God does not exist because Jesus himself never did.

There we have it: probability proving two diametrically opposite conclusions. Alchemy indeed.

Carrier of course has the harder task, and he attacks it with all the gusto of a man uncovering the secret machinations behind the Kennedy assassination. He begins with a label: he defines a mythicist as one who believes in the historical Jesus. This pejorative, like calling climate doom skeptics “deniers”, does half the work for him. Who wants to be a mythicist?...MORE